Bone fixation tool

ABSTRACT

A tool and a method are provided for driving a bone pin into a fractured bone to stabilize the fractured bone by maintaining the fractured bone in a reduced state. The tool may be a handheld device including a cartridge having at least one passageway that receives the bone pin. The tool may also include a pneumatically-powered piston having a needle that is sized for receipt within the passageway of the cartridge, the needle applying sufficient force to the bone pin to drive the bone pin out of the cartridge and into the fractured bone.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 12/787,518, entitled “BONE FIXATION TOOL,” filed May 26, 2010,which claims priority from U.S. Provisional Patent Application Ser. No.61/181,024, entitled “BONE FIXATION,” filed May 26, 2009, the disclosureof which are hereby expressly incorporated each by reference herein inits entirety.

BACKGROUND

1. Field of the Disclosure.

The present disclosure relates to a tool and a method for driving a bonepin into a fractured bone to stabilize the fractured bone. Moreparticularly, the present disclosure relates to a tool and a method fordriving a bone pin into a fractured bone to stabilize the fractured boneby maintaining the fractured bone in a reduced state.

2. Description of the Related Art.

Complex or comminuted bone fractures produce multiple bone fragments. Inoperation, these fragments may be reduced and temporarily securedtogether prior to more permanently fixing the fragments together, suchas with external plating.

Current devices for reducing and temporarily securing together bonefragments possess several disadvantages. External fixation devices, suchas clamps, are bulky and may require invasive surgical procedures. Also,internal fixation devices, such as metallic pins and guide wires, may bedifficult to drive into the bone fragments and may extend externallyfrom the fragments while interfering with external plating.

SUMMARY

The present disclosure relates to a tool and a method for driving a bonepin into a fractured bone to stabilize the fractured bone by maintainingthe fractured bone in a reduced state. In certain embodiments, the bonepin may be used to temporarily stabilize the fractured bone prior tomore permanent fixation. The tool may be a handheld device including acartridge having at least one passageway that receives the bone pin. Thetool may also include a pneumatically-powered piston having a needlethat is sized for receipt within the passageway of the cartridge, theneedle applying sufficient force to the bone pin to drive the bone pinout of the cartridge and into the fractured bone.

According to an embodiment of the present disclosure, a handheld tool isprovided for stabilizing a fractured bone, the handheld tool having aproximal end and a distal end. The handheld tool includes: a housing; atleast one bone pin configured to be driven into the fractured bone tostabilize the fractured bone; a cartridge supported by the housing andincluding at least one passageway that receives the bone pin, thepassageway sized to accommodate axial movement of the bone pin throughthe passageway while limiting radial movement of the bone pin in thepassageway; and a piston that translates axially relative to thehousing, the piston including a head arranged toward the proximal end ofthe handheld tool and a needle arranged toward the distal end of thehandheld tool, the needle sized for receipt within the passageway of thecartridge, the needle applying sufficient force to the bone pin to drivethe bone pin axially from the cartridge and into the fractured bone.

According to another embodiment of the present disclosure, a handheldtool is provided for stabilizing a fractured bone, the handheld toolhaving a proximal end and a distal end. The handheld tool includes ahousing; at least one bone pin configured to be driven into thefractured bone to stabilize the fractured bone; a cartridge supported bythe housing at the distal end of the handheld tool, the cartridgeincluding at least one passageway that receives the bone pin; and apiston that translates axially relative to the housing, the pistonincluding a head arranged toward the proximal end of the handheld tooland a needle arranged toward the distal end of the handheld tool, theneedle sized for receipt within the passageway of the cartridge, theneedle applying sufficient force to the bone pin to drive the bone pinaxially from the cartridge and into the fractured bone.

According to yet another embodiment of the present disclosure, ahandheld tool is provided for driving a bone pin into a fractured boneto stabilize the fractured bone, the handheld tool having a proximal endand a distal end. The handheld tool includes: a housing; a cartridgesupported by the housing and including at least one passageway that issized to receive the bone pin; a piston that translates axially relativeto the housing, the piston including a head arranged toward the proximalend of the handheld tool and a needle arranged toward the distal end ofthe handheld tool, the needle sized for receipt within the passageway ofthe cartridge, the needle applying sufficient force to the bone pin todrive the bone pin axially from the cartridge and into the fracturedbone; a pressurized gas source coupled to the housing for supplying apneumatic force to the head of the piston to axially translate thepiston relative to the housing; a valve assembly having a normallyclosed state to close a flow of pressurized gas from the pressurized gassource to the head of the piston and an open state to open the flow ofpressurized gas from the pressurized gas source to the head of thepiston; and a trigger assembly coupled to the valve assembly to adjustthe valve assembly from the normally closed state to the open state, thevalve assembly automatically returning to the normally closed statefollowing the open state.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1A is a schematic diagram representing an exemplary tool of thepresent disclosure, showing a needle of the tool aligned with a firstbone fragment and a second bone fragment;

FIG. 1B is a schematic diagram of the tool of FIG. 1A, showing theneedle of the tool inserted through the first bone fragment and into thesecond bone fragment;

FIG. 1C is a schematic diagram of the tool of FIG. 1B, showing theneedle of the tool being withdrawn to expose a hole in the bonefragments and showing a biocompatible polymer material being injectedinto the hole;

FIG. 1D is a schematic diagram similar to FIG. 1C, showing the needle ofthe tool withdrawn to expose a hole in the bone fragments and showing abiocompatible polymer material injected into the hole to form a bulbousfiber portion;

FIG. 1E is a schematic diagram of the tool of FIG. 1C, showing abiocompatible polymer material being injected into an adjacent hole toform a loop;

FIG. 2A is a schematic diagram representing another tool of the presentdisclosure, showing the tool aligned with a first bone fragment and asecond bone fragment;

FIG. 2B is a schematic diagram of the tool of FIG. 2A, showing the tooldriving a polymeric rod through the first bone fragment and into thesecond bone fragment;

FIG. 2C is a schematic diagram of the tool of FIG. 2B, showing the toolremoved from the bone fragments while leaving behind the polymeric rodto secure the bone fragments together;

FIG. 3 is a perspective view of an exemplary tool of the presentdisclosure;

FIG. 4 is an exploded perspective view of the tool of FIG. 3 showing avalve assembly and a piston assembly;

FIG. 5 is an exploded perspective view of selected components of thevalve assembly and the piston assembly of FIG. 4;

FIG. 6 is another exploded perspective view of the tool of FIG. 3showing a trigger assembly and a gas supply assembly;

FIG. 7 is a cross-sectional view of the tool of FIG. 3 shown at restbefore being fired;

FIG. 8 is a cross-sectional view of a portion of the tool of FIG. 7;

FIG. 9 is a cross-sectional view of the tool of FIG. 3 shown while beingfired;

FIG. 10 is a cross-sectional view of a portion of the tool of FIG. 9;

FIG. 11 is a cross-sectional view of a portion of the tool of FIG. 3shown in an intermediate state after being fired;

FIG. 12 is a cross-sectional view of a portion of the tool of FIG. 3shown at rest after being fired;

FIG. 13 is a perspective view of a portion of another exemplary tool ofthe present disclosure, the tool including a gas supply assembly havinga regulator;

FIG. 14 is a cross-sectional view of the tool of FIG. 13;

FIG. 15 is a cross-sectional view of the regulator of FIG. 13 shown inand open state;

FIG. 16 is a cross-sectional view of the regulator of FIG. 13 shown in aclosed state; and

FIG. 17 is an exploded perspective view of the regulator of FIG. 13.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary embodiments of the invention and suchexemplifications are not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION

The present disclosure provides a tool and method for reducing andsecuring together bone fragments, which may serve as a temporarysolution prior to more permanent fixation of the bone fragments.According to an exemplary embodiment of the present disclosure, abiocompatible polymer may be inserted into the bone fragments to securethe bone fragments together. The polymer may remain in the patient'sbody over time, or the polymer may absorb into the patient's body.

In one embodiment, the polymer may be injected into the bone fragmentsin a liquid or semi-liquid state and then cured to secure the bonefragments together. Such polymers may cure upon contact with light orwater, for example. A suitable polymer that may be injected into thebone fragments includes a quick-setting cyanoacrylate (commonly soldunder trade names like Super Glue® and Krazy Glue®). It is within thescope of the present disclosure that the polymer may be blended withother materials for injection into the bone fragments, such as elastic,thread-like fibers.

In another embodiment, the polymer may be driven into the bone fragmentsin a solid state to secure the bone fragments together. Suitablepolymers that may be driven into the bone fragments includebiodegradable polymers, such as polylactide (PLA).

Referring initially to FIGS. 1A-1C, an exemplary method for reducing andsecuring together bone fragments is illustrated schematically. Tool 10,which is similar in construction to a syringe, is provided forperforming this method and includes needle 12, tube or cylinder 14defining chamber 15 therein, plunger 16, and housing 18.

In a first step of the illustrative method, and as shown in FIG. 1A,first bone fragment F₁ is aligned with an adjacent, second bone fragmentF₂. Tool 10 is placed near or in contact with first bone fragment F₁.

Next, as shown in FIG. 1B, sufficient force is applied to cylinder 14 oftool 10 to drive needle 12 through first bone fragment F₁ and intosecond bone fragment F₂. Tool 10 may be provided with needles 12 ofvarious sizes to accommodate different fractures and bone types. Forexample, needles 12 may be provided in lengths of approximately 0.25inch, 0.5 inch, 1.0 inch, 1.5 inches, 2.0 inches, or more. Also, needles12 may be provided in diameters of approximately 1 millimeter (mm), 1.5mm, 2 mm, 2.5 mm, 3 mm, or more, for example.

Finally, as shown in FIG. 1C, needle 12 of tool 10 is pulled out of bonefragments F₁, F₂, to expose hole H in bone fragments F₁, F₂. As needle12 retracts from bone fragments F₁, F₂, pressure may be applied toplunger 16 to deliver a biocompatible polymer material P from chamber 15of cylinder 14 into hole H. According to an exemplary embodiment of thepresent method, a biocompatible polymer material P includes fluidcyanoacrylate containing a bundle of thread-like fibers. The internalwalls of cylinder 14 lining chamber 15 may include a non-stick coating,such as polytetrafluoroethylene (PTFE), to prevent polymer material Pfrom drying thereon. Also, chamber 15 of cylinder 14 may contain atleast enough polymer material P to adequately fill hole H. Over time,such as less than a few minutes, the biocompatible polymer material Pcures or hardens in hole H to bind bone fragments F₁, F₂, together.

According to an exemplary embodiment of the present method, bursts ofpolymer material P may be delivered into hole H to form bulbous fiberportions B in hole H, as shown in FIG. 1D. These bulbous fiber portionsB may serve as anchors, preventing the polymer from loosening in hole H.To form bulbous fiber portions B, the initial removal of needle 12 fromhole H may be slowed or delayed while plunger 16 is activated to deliveran initial burst of polymer material P. Then, needle 12 may be retractedto deliver an even, thread-like stream of polymer material P extendingout of hole H.

According to another exemplary embodiment of the present method, and asshown in FIG. 1E, after delivering the biocompatible polymer material Pinto hole H, tool 10 may be moved to a different location on first bonefragment F₁, such as adjacent to second hole H′ in first bone fragmentF₁. Hole H′ may be formed by needle 12 or by another needle. As shown inFIG. 1E, the biocompatible polymer material P may continue beingdispensed from tool 10 during this movement from hole H to hole H′,thereby forming a continuous loop L of polymer material P that extendsacross the surface of first bone fragment F₁ and connects adjacentfilled holes H, H′, similar to the behavior of a sewing machine.Stitching together the polymer material P in adjacent holes H, H′, maystabilize the connection between bone fragments F₁, F₂.

Tool 10 may be powered pneumatically, hydraulically, electrically (e.g.with batteries), and/or electromagnetically. For example, tool 10 maybehave similar to a compressed air nail gun. When a trigger (not shown)of tool 10 is pulled, compressed air may be released to force cylinder14 and needle 12 coupled thereto forward inside housing 18 until needle12 projects beyond housing 18, through first bone fragment F₁, and intosecond bone fragment F₂, as shown in FIG. 1B. When the trigger of tool10 is released, needle 12 and cylinder 14 may retract back into housing18, leaving behind hole H in bone fragments F₁, F₂, as shown in FIG. 1C.Needle 12 and cylinder 14 of tool 10 may be biased in this retractedposition of FIG. 1C relative to housing 18 by any suitable mechanism,including, for example, a spring or a magnet.

To deliver the biocompatible polymer material P into hole H, tool 10 maybe provided with a suitable catch mechanism for blocking retraction ofplunger 16. The catch mechanism may include latch 19, as shown in FIG.1C, or a magnet, for example. When the trigger (not shown) of tool 10 ispulled to move needle 12 and cylinder 14 forward within housing 18, asshown in FIGS. 1A-1B, latch 19 may be in an unlocked position, allowingplunger 16 to travel forward along with needle 12. When the trigger oftool 10 is released to retract needle 12 and cylinder 14 back intohousing 18, as shown in FIG. 1C, latch 19 may move to a locked positionto engage plunger 16. The sliding cylinder 14 will travel over thestationary plunger 16 that is being held in place by latch 19, forcingthe biocompatible polymer material P contained inside chamber 15 ofcylinder 14 to be dispensed from needle 12. After a sufficient amount ofbiocompatible polymer material P is delivered from needle 12, latch 19may be released, allowing plunger 16 to retract into housing 18 relativeto cylinder 14.

Tool 10 may be capable of controlling the depth that needle 12 travelsinto bone fragments F₁, F₂ (FIGS. 1A-1C). According to an exemplaryembodiment of the present disclosure, the depth of needle 12 in bonefragments F₁, F₂, is controlled by limiting the distance that needle 12projects from housing 18. For example, as shown in FIG. 1B, housing 18includes at least one stop 40 that cooperates with flange 42 of cylinder14 to limit the forward travel of needle 12 out of housing 18 and towardbone fragments F₁, F₂.

Referring next to FIGS. 2A-2C, another exemplary method for reducing andsecuring together bone fragments is illustrated schematically. Tool 20,which is similar in construction to a syringe, is provided forperforming this method and includes polymeric needle or rod 22, tube orcylinder 24 defining chamber 25 therein, and plunger 26.

In a first step of the illustrative method, and as shown in FIG. 2A,first bone fragment F₁ is aligned with an adjacent, second bone fragmentF₂. Tool 20 is placed near or in contact with first bone fragment F₁.

Next, as shown in FIG. 2B, sufficient force is applied to plunger 26 oftool 20 to drive rod 22 through the first bone fragment F₁ and into thesecond bone fragment F₂. According to an exemplary embodiment of thepresent method, rod 22 is constructed of a rigid polymer, such aspolylactide (PLA), polystyrene, poly methyl methacrylate, polycarbonate,or a fiber-reinforced polymer, for example. According to anotherexemplary embodiment of the present method, rod 22 is constructed of abiocompatible, non-ferrous metal, such as magnesium.

Finally, as shown in FIG. 2C, tool 20 is pulled away from bone fragmentsF₁, F₂, leaving polymeric rod 22 behind within bone fragments F₁, F₂, tobind bone fragments F₁, F₂, together. According to an exemplaryembodiment of the present method, rod 22 has a textured outer surface toresist loosening or pull-out from bone fragments F₁, F₂. Rod 22 need notbe attached to plunger 26, so that, when tool 20 is pulled away frombone fragments F₁, F₂, rod 22 is left behind. The illustrated chamber 25of cylinder 24 may be exaggerated in size relative to polymeric rod 22.For example, cylinder 24 may be sized such that polymeric rod 22 isradially constrained by cylinder 24, while being permitted to slideaxially within chamber 25 of cylinder 24.

As shown in FIGS. 2A-2C, polymeric rod 22 is provided in a suitablelength to extend into bone fragment F₂ and end substantially flush withbone fragment F₁. It is also within the scope of the present disclosurethat rod 22 may have excess length that may be trimmed before or afterrod 22 is implanted so that rod 22 ends substantially flush with bonefragment F₁. For example, before pulling tool 20 away from bonefragments F₁, F₂, rod 22 may be trimmed along the bone-facing end ofcylinder 24 to remove any excess length from rod 22. As another example,after pulling tool 20 away from bone fragments F₁, F₂, rod 22 may betrimmed along bone fragment F₁ to remove any excess length from rod 22.

Tool 20 may be powered pneumatically, hydraulically, electrically (e.g.with batteries), and/or electromagnetically. For example, tool 20 maybehave similar to a compressed air nail gun. When a trigger (not shown)of tool 20 is pulled, compressed air may be released to force plunger 26forward inside cylinder 24 until rod 22 projects beyond cylinder 24,through first bone fragment F₁, and into second bone fragment F₂, asshown in FIG. 2B. When the trigger of tool 20 is released, plunger 26may retract back into cylinder 24, leaving behind rod 22 in bonefragments F₁, F₂. Plunger 26 of tool 20 may be biased in this retractedposition relative to cylinder 24 by any suitable mechanism, including,for example, a spring or a magnet.

In addition to securing together bone fragments, the methods describedabove may also be used to secure together soft tissue of the body. Themethods described above may also be used to mount orthopedic componentsonto bone, including cut guides, bone plates, and/or cerclage wires.

Referring next to FIGS. 3-12, an exemplary handheld pneumatic tool 100is provided for reducing and securing together bone fragments. Tool 100extends between a first, proximal end 102 and a second, distal end 104.As shown in FIG. 3, proximal end 102 of tool 100 includes left-sidehousing 106 a, right-side housing 106 b, and trigger 108. Left-sidehousing 106 a and right-side housing 106 b of tool 100 cooperate todefine handle 110. Distal end 104 of tool 100 includes barrel 112 andnose 114. In operation, with distal end 104 of tool 100 positionedagainst a fractured bone, a surgeon may grip handle 110 and pull trigger108.

With reference to FIG. 4, tool 100 also includes cartridge 116, dial118, valve assembly 120, and piston assembly 130. Valve assembly 120 oftool 100 includes valve body 122, valve return spring 124, plug bolt126, and plug 128. Piston assembly 130 of tool includes piston 132,piston return spring 134, damper 136, and guide 138. Each component ofFIG. 4 is described further below.

With reference to FIG. 6, tool 100 further includes gas supply assembly140 and trigger assembly 150. Gas supply assembly 140 of tool 100includes cap 142, gas canister 144, puncture valve 146, and regulator148. Trigger assembly 150 of tool 100 includes trigger 108, triggerspring 151, an arcuate linkage 152, rotating pawl 153, shaft 154, stoppin 155, left-side casing 156 a, right-side casing 156 b, left-sideholder 157 a, right-side holder 157 b, a lock or seer 158, and aU-shaped seer spring 159. Each component of FIG. 6 is described furtherbelow.

Left-side housing 106 a and right-side housing 106 b of tool 100cooperate to conceal and support valve assembly 120, gas supply assembly140, and trigger assembly 150 of tool 100. As shown in FIG. 3, housing106 a defines external opening 160 so that dial 118 may be accessiblethrough housing 106 a. Housings 106 a, 106 b, cooperate to define firstgas channel 162 that connects gas canister 144 to regulator 148 andsecond gas channel 164 that connects regulator 148 to valve body 122, asshown in FIG. 6. In operation, pressurized gas travels from gas canister144 to regulator 148 via first gas channel 162 of housings 106 a, 106 b,and from regulator 148 to valve body 122 via second gas channel 164 ofhousings 106 a, 106 b.

Barrel 112 of tool 100 is a hollow component that extends from housings106 a, 106 b, as shown in FIG. 3. Barrel 112 includes proximal portion166 situated toward proximal end 102 of tool 100 and distal portion 168situated toward distal end 104 of tool 100. Barrel 112 is sized toreceive piston assembly 130 therein. More particularly, proximal portion166 of barrel 112 is sized to receive piston return spring 134 anddamper 136 of piston assembly 130 therein, and distal portion 168 ofbarrel 112 is sized to receive guide 138 of piston assembly 130 therein,with piston 132 of piston assembly 130 extending along substantially theentire length of barrel 112 between both proximal portion 166 and distalportion 168 of barrel 112. As shown in FIG. 4, proximal portion 166 ofbarrel 112 may be larger in diameter than distal portion 168 of barrel112 to accommodate piston 132, piston return spring 134, and damper 136of piston assembly 130.

Nose 114 of tool 100 is a hollow component that extends from barrel 112to define distal end 104 of tool 100, as shown in FIG. 3. Nose 116includes bone-contacting surface 169 that is configured to rest againstthe patient's bone. Bone-contacting surface 169 of nose 116 may betextured (e.g. toothed, spiked) to gain purchase on the patient's bonewithout slippage. Nose 114 is sized to receive cartridge 116 therein.Also, nose 114 may be sized to receive at least a portion of barrel 112therein, including the narrow, distal portion 168 of barrel 112.

Cartridge 116 of tool 100 is a cannulated component that is sized forreceipt within nose 114 of tool 100, such that cartridge 116 may bepositioned at distal end 104 of tool 100. As shown in FIG. 5, cartridge116 includes cannula 170 that is bordered by at least one flat 172.Around cannula 170, cartridge 116 further includes a plurality ofelongate slots or passageways 174. Each passageway 174 of cartridge 116is sized to receive a biocompatible rod or pin 176 therein. Eachpassageway 174 may be distinct, or, as shown in FIG. 5, multiplepassageways 174 may be interconnected. According to an exemplaryembodiment of the present disclosure, passageways 174 of cartridge 116are sized to limit each pin 176 to axial movement through thecorresponding passageway 174, thereby stabilizing pins 176 and ensuringthat pins 176 are delivered along a straight path to avoid bendingand/or breaking After use, cartridge 116 may be removed from tool 100and either refilled with new pins 176 or replaced.

Pin 176 is configured to be driven into bone fragments to secure thebone fragments together. Pin 176 may be constructed of a biocompatiblepolymer, and in certain embodiments, the biocompatible polymer may bebiodegradable. For example, pin 176 may be constructed of abiodegradable polymer, such as polylactide (PLA). Pin 176 may also beconstructed of polystyrene, poly methyl methacrylate, polycarbonate, ora fiber-reinforced polymer, for example. It also is within the scope ofthe present disclosure that pin 176 may be constructed of abiocompatible, non-ferrous metal, such as magnesium. Each pin 176 mayhave a length as small as approximately 0.5 inch, 0.6 inch, 0.7 inch,0.8 inch, 0.9 inch, or less, and as large as approximately 1.0 inch, 1.1inches, 1.2 inches, 1.3 inches, 1.4 inches, 1.5 inches, or more. Eachpin 176 may have a diameter as small as approximately 0.03 inch, 0.04inch, 0.05 inch, or 0.06 inch, and as large as approximately 0.07 inch,0.08 inch, 0.09 inch, 0.10 inch, or more. Depending on the size of pin176 and the material used to construct pin 176, the weight of pin 176may be less than about 0.01 gram, such as approximately 0.005 gram,0.006 gram, or 0.007 gram. An exemplary pin 176 may not impedesubsequent fixation. For example, pin 176 may be sufficiently small insize and/or low in density that the surgeon may drill through pin 176during a subsequent procedure.

Dial 118 of tool 100 includes a generally hollow head 180 that is sizedfor receipt within housings 106 a, 106 b, and shaft 182 that extendsaxially through barrel 112 and into nose 114, as shown in FIG. 4. Aplurality of spaced apart rims 181 join head 180 to shaft 182, as shownin FIG. 5, to accommodate airflow through head 180 and around shaft 182of dial 118.

Dial 118 couples to cartridge 116 for rotation therewith. For example,as shown in FIG. 5, shaft 182 of dial 118 extends through cannula 170 ofcartridge 116 and includes at least one flat 183 that mates with flat172 of cartridge 116 to transfer rotational movement of dial 118 tocartridge 116. Head 180 of dial 118 may include a textured or knurledexterior surface 184 to facilitate the turning of dial 118. As shown inFIG. 3, knurled exterior surface 184 of dial 118 is exposed throughexternal opening 160 in housing 106 a so that the surgeon may access andturn dial 118.

Dial 118 may include a suitable detent mechanism to ensure properalignment of cartridge 116. For example, as shown in FIG. 5, head 180 ofdial 118 includes a plurality of evenly spaced alignment holes 186therein. Each alignment hole 186 may be sized to receive a ball 187(FIG. 8) or another suitable detent to ensure that dial 118, andcartridge 116 coupled thereto, are rotated to one of a discrete numberof positions.

Valve assembly 120 of tool 100 is received within housings 106 a, 106 b,and includes valve body 122, valve return spring 124, plug bolt 126, andplug 128. As shown in FIG. 7, valve body 122 is a generally hollowcomponent that defines gas chamber 188 therein. Gas chamber 188 of valvebody 122 includes inlet 188 a that communicates with second gas channel164 of housings 106 a, 106 b, to receive pressurized gas from gas supplyassembly 140. Gas chamber 188 of valve body 122 also includes a sealed,chamfered outlet 188 b that communicates with piston assembly 130 todeliver pressurized gas from gas supply assembly 140 to piston assembly130.

Plug bolt 126 of valve assembly 120 is a generally hollow component thatsurrounds and translates axially across valve body 122. As shown in FIG.5, plug bolt 126 includes head 190 and platform 192 for supporting plug128, as discussed further below. Plug bolt 126 also includes a pluralityof spaced apart rims 194 that extend radially outwardly from platform192 to accommodate airflow through plug bolt 126.

Plug 128 of valve assembly 120 is sized for receipt within outlet 188 bof valve body 122, as shown in FIG. 7. Plug 128 translates axiallyrelative to valve body 122 to close and open valve assembly 120. Valveassembly 120 closes when plug 128 seals outlet 188 b of valve body 122closed, as shown in FIG. 8, thereby preventing airflow from gas chamber188 of valve body 122. Valve assembly 120 opens when tapered end 196 ofplug 128 translates into outlet 188 b of valve body 122 and opens outlet188 b, as shown in FIG. 9, thereby allowing pressurized gas to escapefrom gas chamber 188 of valve body 122.

Piston assembly 130 of tool 100 is received within barrel 112 and nose114 and includes piston 132, piston return spring 134, damper 136, andguide 138, as shown in FIG. 4.

Piston 132 of piston assembly 130 is a cannulated component thattranslates axially within barrel 112. Piston 132 includes head 200,shaft 202, and a radially offset needle 204 that is coupled to shaft202. Needle 204 is sized for receipt within each individual passageway174 of cartridge 116. According to an exemplary embodiment of thepresent disclosure, passageways 174 of cartridge 116 are sized to limitneedle 204 to axial movement therein, thereby stabilizing needle 204. Asshown in FIG. 7, shaft 182 of dial 118 extends entirely through thecannulated piston 132 to reach cartridge 116. In operation, the surgeonrotates dial 118 to selectively align a desired passageway 174 ofcartridge 116 with needle 204 of piston 132.

Damper 136 of piston assembly 130 is a cannulated component that issized to receive shaft 202 of piston 132 therein, as shown in FIG. 4.Damper 136 may be constructed of plastic or rubber, for example, toresist and slow axial translation of piston 132.

Guide 138 of piston assembly 130 is a cannulated component that is sizedand shaped to receive both shaft 202 and needle 204 of piston 132therein, as shown in FIG. 5. Guide 138 may be contoured to closely matchthe outer profile of piston 132, thereby guiding and stabilizing axialtranslation of piston 132.

Gas supply assembly 140 of tool 100 is received within housings 106 a,106 b, and includes cap 142, gas canister 144, puncture valve 146, andregulator 148. As shown in FIG. 6, cap 142 is removably coupled tohousings 106 a, 106 b, for removing and replacing gas canister 144.

Gas canister 144 of gas supply assembly 140 contains a supply ofpressurized gas. Preferably, gas canister 144 contains pressurizedcarbon dioxide gas (CO₂) or nitrogen gas (N2). Advantageously, gascanisters 144 are inexpensive, are readily commercially available, andare able to power tool 100 independently without any other secondarypower source, such as a battery. Pressurized gas is generallycommercially available in 12-gram supplies, although tool 100 may bedesigned to accommodate gas canisters 144 of various types and sizes.The pressure inside gas canister 144 may be as low as approximately 300psi, 400 psi, 500 psi, or 600 psi, and as high as approximately 700 psi,800 psi, 900 psi, 1000 psi, or more, although the pressure inside gascanister 144 will vary with temperature. A 12-gram supply of pressurizedCO₂, for example, may have a pressure of about 850 psi at roomtemperature. When each new gas canister 144 is inserted into housings106 a, 106 b, puncture valve 146 will open gas canister 144 to initiateairflow from gas canister 144 to regulator 148 via first gas channel162, as shown in FIG. 6.

Regulator 148 of gas supply assembly 140 is provided to control thepressure of the gas that is delivered to valve assembly 120. When thepressure in valve body 122 of valve assembly 120 reaches a desiredthreshold, such as approximately 100 psi, 200 psi, 300 psi, 400 psi, 500psi, or 600 psi, for example, regulator 148 cuts off the continued flowof pressurized gas to valve body 122. Therefore, even if the pressure ingas canister 144 fluctuates, regulator 148 is able to deliverpressurized gas to valve body 122 at a substantially constant pressure.Regulator 148 may be similar to those used in paintball guns, forexample.

Trigger assembly 150 of tool 100 is received within housings 106 a, 106b, and includes trigger 108, trigger spring 151, an arcuate linkage 152,rotating pawl 153, shaft 154, stop pin 155, left-side casing 156 a,right-side casing 156 b, left-side holder 157 a, right-side holder 157b, seer 158, and a U-shaped seer spring 159, as shown in FIG. 6. Trigger108 of trigger assembly 150 is pivotally coupled to housings 106 a, 106b, to drive rotation of pawl 153, as discussed further below.

Pawl 153 of trigger assembly 150 includes an oblong central opening 210,an outwardly extending finger 212, and notch 214, as shown in FIG. 6.Shaft 154 extends through the oblong central opening 210 of pawl 153,such that pawl 153 is able to rotate about shaft 154 as well astranslate relative to shaft 154. Pawl 153 may be at least partiallycovered by casings 156 a, 156 b, including guide arm 216 that protrudesfrom casing 156 b.

Lock or seer 158 of trigger assembly 150 is pivotally coupled tohousings 106 a, 106 b. Seer 158 includes first end 218 a that contactsfinger 212 of pawl 153 and second end 218 b that contacts plug bolt 126of valve assembly 120, as shown in FIG. 8. Second end 218 b of seer 158includes blocking surface 220 that faces proximal end 102 of tool 100and ramped surface 222 that faces valve assembly 120 of tool 100.

The operation of tool 100 will now be described with reference to FIGS.7-12. FIGS. 7 and 8 depict tool 100 at rest before being fired, FIGS. 9and 10 depict tool 100 while being fired, FIG. 11 depicts tool 100 in anintermediate state after being fired, and FIG. 12 depicts tool 100 atrest after being fired.

With reference to FIGS. 7 and 8, tool 100 is shown at rest before beingfired. In this state of rest, trigger 108 is biased outwardly under theforce of trigger spring 151. Arcuate linkage 152 is coupled to trigger108 and pulls finger 212 of pawl 153 downwardly and out of the way ofseer 158. As shown in FIG. 8, seer 158 is biased upwardly under theforce of seer spring 159, such that blocking surface 220 of seer 158engages head 190 of plug bolt 126 to prevent plug bolt 126 fromtranslating axially toward distal end 104 of tool 100.

Pressurized gas travels from gas canister 144 to regulator 148 via firstgas channel 162 of housings 106 a, 106 b, and from regulator 148 intogas chamber 188 of valve body 122 via second gas channel 164 of housings106 a, 106 b. However, pressurized gas is not able to escape from gaschamber 188 of valve body 122, because platform 192 of plug bolt 126keeps plug 128 sealed within outlet 188 b of valve body 122. Seer 158prevents plug bolt 126, and in turn plug 128, from translating axiallytoward distal end 104 of tool 100 to escape from valve body 122.

Without the flow of pressurized gas from valve body 122, piston 132retracts into tool 100 under the force of piston return spring 134, asshown in FIG. 7. Needle 204 of piston 132 is aligned with passageway 174of cartridge 116 and pin 176 located therein, but is also retracted intotool 100 under the force of piston return spring 134.

With reference to FIGS. 9 and 10, tool 100 is shown while being fired.In this fired state, the surgeon pulls trigger 108 inwardly against theforce of trigger spring 151. Arcuate linkage 152 forces finger 212 ofpawl 153 to rotate upwardly, which causes first end 218 a of seer 158 topivot upwardly and second end 218 b of seer 158 to pivot downwardlyagainst the force of seer spring 159. Pivoting seer 158 in this mannermoves blocking surface 220 of seer 158 away from plug bolt 126, therebyfreeing plug bolt 126 to translate axially toward distal end 104 of tool100, as shown in FIG. 10.

The elevated pressure in gas chamber 188 of valve body 122 forces plugbolt 126 and plug 128 axially toward distal end 104 of tool 100, whichfrees plug 128 from outlet 188 b of valve body 122. As discussed above,this axial movement of plug bolt 126 is no longer blocked by seer 158.Pressurized gas escapes from outlet 188 b of valve body 122 and flowsaround plug 128, through plug bolt 126, through head 180 of dial 118,and around shaft 182 of dial 118.

Pressurized gas then reaches head 200 of piston 132, which forces piston132 to translate axially toward distal end 104 of tool 100 against theforce of piston return spring 134, as shown in FIG. 9. This translatingmovement of piston 132 may be slowed by the presence of damper 136around shaft 202 of piston 132 and may be guided and stabilized by thepresence of guide 138 around shaft 202 and needle 204 of piston 132. Inthe fired position, needle 204 enters passageway 174 of cartridge 116and drives pin 176 therefrom. With distal end 104 of tool 100 positionedagainst a fractured bone, the force against piston 132 may be sufficientto drive pin 176 into the bone for securing together adjacent bonefragments. For example, pin 176 may be driven through approximately 1 mmof cortical bone at pressures of about 70 psi and through approximately4 mm of cortical bone at pressures between about 400 psi and 500 psi.

When head 200 of piston 132 is driven forward a sufficient distance todeliver pin 176, vent 224 in barrel 112 may be exposed, as shown in FIG.9. Pressurized gas may escape from behind head 200 of piston 132 throughvent 224, thereby reducing the pressure in tool 100. According to anexemplary embodiment of the present disclosure, vent 224 may directpressurized gas radially outwardly from barrel 112 so as not tointerfere with the patient situated near distal end 104 of tool 100 orthe surgeon situated near proximal end 102 of tool 100.

With reference to FIG. 11, tool 100 is shown in an intermediate stateafter being fired. According to an exemplary embodiment of the presentdisclosure, tool 100 reaches this intermediate state automatically andrapidly after the fired state, even if the surgeon continues to pulltrigger 108. Arcuate linkage 152 continues to force finger 212 of pawl153 to rotate upwardly until stop pin 155 enters notch 214 of pawl 153,which limits further rotation of pawl 153. As shown in FIG. 11, finger212 of pawl 153 rotates beyond first end 218 a of seer 158, allowingseer 158 to return to its original starting position under the force ofseer spring 159 with second end 218 b of seer 158 extending back intothe path of plug bolt 126.

After tool 100 is fired, the pressure in gas chamber 188 of valve body122 drops because pressurized gas is able to escape through vent 224(FIG. 9). Under this now-reduced pressure, valve return spring 124 isable to force plug bolt 126 and plug 128 back into outlet 188 b of valvebody 122 to shut off the supply of pressurized gas. Specifically, and asshown in FIG. 11, valve return spring 124 forces head 190 of plug bolt126 over ramped surface 222 of seer 158, with plug bolt 126 carryingplug 128 back into outlet 188 b of valve body 122.

Without the continued flow of pressurized gas from valve body 122,piston 132 retracts into tool 100 under the force of piston returnspring 134, as shown in FIG. 11. Needle 204 (FIG. 7) of piston 132 alsoretracts into tool 100 under the force of piston return spring 134,leaving behind an empty passageway 174 of cartridge 116.

With reference to FIG. 12, tool 100 is shown at rest after being fired.According to an exemplary embodiment of the present disclosure, tool 100reaches this rest state automatically and rapidly after the intermediatestate, even if the surgeon continues to pull trigger 108. Due to theoblong shape of central opening 210 of pawl 153, pawl 153 translatesdownwardly over shaft 154. Finger 212 of pawl 153 also translatesdownwardly until reaching a position beneath first end 218 a of seer 158to await the next pull of trigger 108.

Valve return spring 124 continues to force plug bolt 126 and plug 128back into outlet 188 b of valve body 122 to shut off the supply ofpressurized gas. Specifically, and as shown in FIG. 12, valve returnspring 124 forces head 190 of plug bolt 126 over ramped surface 222 ofseer 158 and, eventually, behind blocking surface 220 of seer 158. Oncehead 190 of plug bolt 126 is locked behind blocking surface 220 of seer158, valve body 122 can only be reopened by pulling trigger 108 again.

Before firing tool 100 again, the surgeon may turn dial 118 to rotatecartridge 116. Rotating cartridge 116 will advance the next passageway174 of cartridge 116, and pin 176 located therein, into alignment withneedle 204.

Referring next to FIGS. 13-17, a portion of another exemplary handheldpneumatic tool 100′ is provided for reducing and securing together bonefragments. Tool 100′ of FIGS. 13-17 is similar to tool 100 of FIGS.3-12, with like reference numerals indicating like elements, except asdescribed below.

As shown in FIG. 13, proximal end 102′ of tool 100′ includes right-sidehousing 106 b′ that cooperates with a corresponding left-side housing(not shown) to support a suitable trigger assembly (not shown, but whichmay be similar to trigger assembly 150 of tool 100), piston assembly(not shown, but which may be similar to piston assembly 130 of tool100), valve assembly 120′ which includes valve body 122′, and gas supplyassembly 140′ which includes gas canister 144′ and regulator 148′.Housing 106 b′ defines gas channel 162′ that connects gas canister 144′to regulator 148′. Housing 106 b′ also defines vent 224′ anddepressurization chamber 226′ in handle 110′.

As shown in FIG. 17, regulator 148′ of gas supply assembly 140′ includesregulator body 300′, diaphragm 302′, actuator spring 304′, seal 306′,bolt 308′, and selector 310′. Each component of regulator 148′ isdescribed further below.

Regulator body 300′ of regulator 148′ is a generally hollow componentthat defines gas chamber 312′ therein, as shown in FIG. 15. Gas chamber312′ of regulator body 300′ includes inlet 312 a′ that communicates withgas channel 162′ of housing 106 b′ to receive pressurized gas from gascanister 144′ (FIG. 14). Gas chamber 312′ of regulator body 300′ alsoincludes outlet 312 b′ that communicates with valve body 122′. Accordingto an exemplary embodiment of the present disclosure, regulator body300′ may be integrally formed with valve body 122′, such that outlet 312b′ of regulator body 300′ defines or is directly connected to inlet 188a′ of valve body 122′.

Diaphragm 302′ of regulator 148′ is sized for receipt within gas chamber312′ of regulator body 300′ and is configured to translate axiallytherein. As shown in FIG. 17, diaphragm 302′ defines one or more axialpassageways 314′ through regulator 148′.

Bolt 308′ of regulator 148′ is also sized for receipt within gas chamber312′ of regulator body 300′. Bolt 308′ includes head 316′ and shaft318′. Head 316′ of bolt 308′ defines annular passageway 320′ and one ormore axial passageways 322′ through regulator 148′ Annular passageway320′ cooperates with each axial passageway 322′ to define one or moreL-shaped gas pathways through regulator 148′.

Selector 310′ of regulator 148′ is sized for receipt within bolt 308′.Selector 310′ includes socket 324′ that is configured to receive asuitable tool (not shown) for screwing selector 310′ into bolt 308′.Selector 310′ is configured to adjust the threshold pressure ofregulator 148′, and therefore the threshold pressure in valve body 122′.Tightening selector 310′ into bolt 308′ forces actuator spring 304′further out of bolt 308′, which increases the threshold pressure invalve body 122′. Loosening selector 310′ from bolt 308′ allows actuatorspring 304′ to retract further into bolt 308′, which decreases thethreshold pressure in valve body 122′.

The operation of tool 100′ is described with reference to FIGS. 14-16.Pressurized gas flows from gas canister 144′ to inlet 312 a′ ofregulator body 300′ via gas channel 162′, as shown in FIG. 14.Pressurized gas then flows through annular passageway 320′ and axialpassageways 322′ of bolt 308′ toward diaphragm 302′. Initially, actuatorspring 304′ forces diaphragm 302′ apart from bolt 308′, as show in FIG.15, so that pressurized gas is able to flow around seal 306′, throughaxial passageways 314′ of diaphragm 302′, and into valve body 122′. Overtime, as pressurized gas continues to enter valve body 122′, thepressure at outlet 312 b′ of regulator body 300′ and inlet 188 a′ ofvalve body 122′ increases, forcing diaphragm 302′ toward bolt 308′against the force of actuator spring 304′. Eventually, when a thresholdpressure is reached, seal 306′ becomes sufficiently compressed to blockaxial passageways 314′ of diaphragm 302′, as shown in FIG. 16. At thisstage, regulator 148′ stops the continued flow of pressurized gas toinlet 188 a′ of valve body 122′, thereby limiting the pressure in valvebody 122′.

When the surgeon operates the trigger assembly of tool 100′ (not shown,but which may be similar to trigger assembly 150 of tool 100), thepressurized gas is able to escape from outlet 188 b′ of valve body 122′.For example, operating the trigger assembly of tool 100′ may free a bolt(not shown, but which may be similar to bolt 128 of tool 100) fromoutlet 312 b′ of regulator body 300′. The pressurized gas that escapesvalve body 122′ may pneumatically deliver a pin (not shown, but whichmay be similar to pin 176 of tool 100) into the patient's bone.

After delivering the pin, pressurized gas may escape through vent 224′in handle 110′, as shown in FIG. 14, thereby reducing the pressure intool 100′. The pressure of the escaping gas may be reduced indepressurization chamber 226′ before the gas ever exits handle 110′.According to an exemplary embodiment of the present disclosure, vent224′ and depressurization chamber 226′ may direct the escaping gasdownwardly from handle 110′ so as not to interfere with the patient orthe surgeon holding handle 110′.

While this invention has been described as having preferred designs, thepresent invention can be further modified within the spirit and scope ofthis disclosure. This application is therefore intended to cover anyvariations, uses, or adaptations of the invention using its generalprinciples. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A tool for stabilizing a fractured bone,comprising: a barrel having a proximal end and a distal end, the distalend of the barrel including a passageway for receiving a bone pinconfigured to be driven into the fractured bone to stabilize thefractured bone, the passageway being sized to accommodate axial movementof the bone pin through the passageway while limiting radial movement ofthe bone pin in the passageway; a piston having a proximal end and adistal end and configured to translate axially relative to the barrel,the proximal end of the piston including a head and the distal end ofthe piston including a needle formation sized for receipt within thepassageway of the barrel; a cartridge for receiving the bone pin, thecartridge configured to be supported at the distal end of the barrel,wherein the cartridge includes an at least partially cylindrical bodyhaving an outer surface sized to fit within a nose portion at the distalend of the barrel, and an inner surface at least partly defining atleast one passageway for receiving the bone pin; and a dial coupled tothe tool for rotating the cartridge to selectively align the at leastone passageway with the needle formation, wherein the needle formationconfigured to apply sufficient force to the bone pin to drive the bonepin axially from the barrel and into the fractured bone.
 2. The tool ofclaim 1, wherein the piston is axially translatable within the barrel.3. The tool of claim 1, wherein the barrel comprises a single passagewayfor receiving a single bone pin configured to be driven into thefractured bone to stabilize the fractured bone.
 4. The tool of claim 1,further comprising a pressurized gas source for supplying a pneumaticforce to the head of the piston to axially translate the piston relativeto the barrel.
 5. The tool of claim 4, further comprising a handleconfigured to receive the pressurized gas source.
 6. The tool of claim5, wherein the handle comprises a cylindrical recess, sized to receivethe pressurized gas source, and extending through at least a portion ofthe handle.
 7. The tool of claim 5, further comprising a gas connectionport provided within the handle to which the pressurized gas source canbe coupled.
 8. The tool of claim 5, wherein the handle is configured tobe coupled to the barrel.
 9. The tool of claim 4, further comprising apuncture device operable to release gas from the pressurized gas source.10. The tool of claim 4, further comprising a trigger assembly torelease the piston.
 11. The tool of claim 10, wherein the triggerassembly comprises a component that is movable transversely relative tothe piston in response to operation of the trigger assembly to permitand restrain axial translation of the piston.
 12. The tool of claim 10,wherein the pressurized gas source is configured to supply pneumaticforce to the head of the piston both when the piston is restrained bythe trigger assembly, and when driving the bone pin into the fracturedbone.
 13. The tool of claim 10, further comprising a pressurized volumefor holding gas released by the pressurized gas source under pressurewhile the piston is restrained by the trigger assembly.